Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint=false), the description discloses a non-obvious behavioral trait: fleets over 300 vehicles are silently truncated to the first 300 by registration, with incomplete coverage and an unknown total reported. That truncation/coverage caveat is genuinely useful and not inferable from structured fields, though "Read-only" merely restates the annotation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Dense and front-loaded: the scope, action types and cap come first, followed by the coverage caveat and the safety note. Every sentence earns its place except the trailing "Read-only," which duplicates the readOnlyHint annotation.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need no explanation. The description covers scope, action categories, the compliance window, the truncation behavior, and the coverage caveat an agent needs before making fleet-wide statements, leaving nothing essential missing for a single-parameter read tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0% for the single `limit` parameter (default 20, max 20), so the description must carry the burden. It mentions "top 20" but never explains that `limit` controls the count, nor the 1-20 bounds, leaving the parameter's semantics only partially implied.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (Return) and resource (MOT, tax, insurance, service and open maintenance actions) plus an explicit scope ceiling (fleets up to 300 vehicles). An agent can immediately distinguish this fleet-level brief from the vehicle-level sibling get_vehicle_action_detail without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives real operational context: compliance actions cover overdue dates plus the next 30 days, and the instruction "Check coverage before making fleet-wide claims" tells the agent how to consume the result responsibly. It does not, however, explicitly name when to prefer this over the sibling get_vehicle_action_detail or search_vehicles.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.